I am building an epp flying wing, I need to determine what size electric engine to use. My wing will be 80 inches. Is there a formula? Weight to wing area? In addition, I want to do long range flights, how do I determine which type of electric engine to use. Are the more expensive ones any better than the cost effective Chinese?

Any thoughts would be appreciated.

Last edited by peternemser; Nov 03, 2011 at 06:50 PM.
Reason: Left out some information

There are a few more factors that will affect your final choice besides wingspan.

You say you want to do long-range flights, so let's start there. How long is "long"? A mile? Ten miles? More? Virtually anything is possible, but a plane set up to fly a mile will need a vastly different motor than one intended to make it, say, fifty miles from the starting point.

An eighty-inch wing powered like a slowish sport plane (40mph cruise) might cover around ten miles in one flight, figuring on an average speed of 40mph for about 15 minutes.

Additional information would be helpful, though. What type of wing is this (chevron, delta, plank, forward-swept etc.)? What kind of aspect ratio are we dealing with? Pics would certainly help.

I would like to use a programmable gps unit to load up missions and fly. Honestly, I am venturing into this realm, so sure a high gain system sounds good. Can you provide some reference links. I am using this as a proof of concept for the local mountain rescue. We get a lot of people lost in the mountains where I live. Real helicopters are expensive....

You will want to check out the FPV subforum, there is a mile of information there for you to get stuck into!

The big thing is to start out small... try checking out the HobbyKing website and looking at their 5.8GHz 200mW transmitter/recevier package. This will give you around 1km of range in stock form and can easily be upgraded with better antennas (bought or homemade) and tracking devices to give up to 8km of range or more. The best thing is its inexpensive so you can upgrade later on if/when you want.

Anyway, the reason to start out small is that it is easy to get disoriented - and thats with a system that functions perfectly! Trying out a new system on a new plane will really test you... the last thing you want to do is try going long range on top of that. There is also the risk that the system will fail and you will lose the plane you worked hard to buy and build - taking small steps will help all but eliminate this as a factor.

If you wanted to check out my blog for some basic FPV info then just click on my username. I've put a bit up there recently so it should be of some help at least.